Mr. M. M. Piittison Muir on Chemical Classification. 265 



tremely slight. I have shown, in papers communicated to 

 the Chemical Society, that the hydrates of this element are 

 possessed of no acid properties. And tliis is what we sliould 

 expect from a consideration of the position of bismuth in the 

 periodic curve of Meyer. Further, the curve of the sixth 

 section is almost certainly incomplete ; there is a great gap 

 between barium and tantalum. The determinations of tlie 

 atomic weights of many members of this section also stand in 

 much need of revisal. The next metal after bismuth, in order 

 of atomic weight, is uranium (that is, if the number 240 be 

 adopted for this metal). But the atomic volume of uranium 

 places it much below bismuth on the curve. Is it not, then, 

 very probable that a new element, or elements, is yet to be dis- 

 covered with high atomic weight and comparatively low specific 

 gravity, which will complete the section, the maximum point of 

 which we can scarcely regard as occupied by bismuth ? 



The electro-positive or negative character of an element 

 is evidently closely related to its general chemical deportment. 

 MendelejefF has showm that, if the elements be arranged in 

 the ascending order of their atomic weights, the power of 

 combining v/ith oxygen possessed by the elements varies 

 periodically wdth the atomic weight. 



If the formulae of the oxides be represented as containing 

 two atoms of the element other than oxygen, then we find 

 that, as the atomic weight increases, the amount of oxygen 

 fixed increases by whole atoms, but that no element is capable 

 of fixing more than eight atoms of oxygen to two atoms of itself. 



Analogous periodic connexion may be traced between the 

 atomic weights, the hydrides (or ethides), and hydrates of 

 the elements, also between the atomic weights, oxides, and 

 chlorides of the elements *. 



The fact that the chlorides corresponding to certain oxides 

 are unknown is one of considerable interest. Taking the 

 nitrogen group of elements, for instance, we have the follow- 

 ing oxides and chlorides. (These formulae are not regarded 

 as representing molecular weights.) 



Oxides. 



— — P2 O3 



— y^o^ V2O3 



As2 0(?) — AS2O3 



- m,o,{^) - 



— — Sb^ O3 

 Bis O2 Bis O3 



* See Bie modernen Theorien, 2nd edit. pp. 830—334. 



N204 



N,0, 



■ — ■ 



P.O. 



V20, 



V3O, 





AhO. 



Nba Oi 



NbjOi 



Sb^O, 



SbjO, 



Taj O4 



Ta^Os 



BijOi 



Bi2 O5 



